This invention relates to flame retardant compositions containing at least one tetrahalophthalate ester and an SMA resin. Additionally, this composition may also contain one or more brominated and/or chlorinated compounds in an amount to provide additional flame retardancy to the SMA resin. This invention also comprehends the method of improving the flame retardancy and processability of the SMA resins by using these tetrahalophthalate esters alone or in combination with one or more bromine and/or chlorine compounds.
Styrene-Maleic Anhydride (SMA) copolymers find extensive use in the manufacture of molded articles and foamed products. In general, they are prepared by copolymerizing styrene and maleic anhydride in the proper ratio and under the appropriate conditions. The preparation and description of SMA copolymers are described in U.S. Pat. Nos. 2,769,804; 2,971,939; 3,336,267; and 3,966,843, the teachings of which are incorporated herein by reference.
SMA polymers burn rapidly and are generally not used in applications which require fire retardant polymers such as radio and television cabinets, tables, chairs, appliance housings and the like. (See U.S. Pat. No. 4,151,218 which is incorporated by reference).
The use of brominated and/or chlorinated compounds by themselves or in combination with other materials such as organic phosphates, antimony compounds, etc., as flame retardants for SMA resin compositions are well known in the art and are exemplified by U.S. Pat. Nos. 3,766,249; 3,966,843; 4,032,481; 4,038,245; 4,089,912; 4,113,672; 4,136,135; 4,151,218; and 4,323,655. The aforesaid patents are incorporated herein by reference.
Tetrahalophthalate esters have been used as flame-proofing materials. For example, U.S. Pat. No. 4,098,704 describes the use of these materials as textile finishing agents. U.S. Pat. Nos. 4,298,517 and 4,397,977 disclose these compounds as flame retardants for halogenated resins. However, no teachings have been found which show the use of these compounds as flame retardants or processing aids for SMA resins.